Cannula insertion device and related methods

ABSTRACT

A cannula insertion device includes a housing defining an opening for receiving therethrough a cannula and further defining a channel, and a cannula forming a lumen, the cannula adapted for sliding movement within the housing from a retracted position to an extended position. When the cannula is in the retracted position, the lumen is located remotely from the channel and the channel is in fluidic communication with the opening. When the cannula is in the extended position, the lumen is in fluidic communication with the channel.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of German PatentApplication Ser. No. 10 2007 049 446.9, filed Oct. 16, 2007, thedisclosure of which is hereby incorporated by reference herein in itsentirety.

FIELD OF THE INVENTION

This invention relates generally to systems and methods for inserting acannula into a patient and, more specifically, to a device thatautomatically inserts a cannula, as well as connects the cannula lumento a channel within an infusion device.

BACKGROUND

In many cases, it is necessary to insert a catheter or cannula into thebody, or a body part of, a patient. By means of the so-inserted cannula,it is then possible to infuse medicinally-required fluid or material.Another reason for the employment of a cannula may be to aid ininsertion of a micro-dialysis probe into the body.

To insert a cannula into a patient, a rigid needle is placed within thelumen of the cannula, and the needle and cannula combination is forcedinto the skin of a patient. Once the cannula combination is fullyinserted, the needle is retracted, leaving the cannula in place. Whenperformed manually, the penetration of the catheter-carrying needle intothe body, however, may be considered uncomfortable for a patient, or maycause some other anxiety. Also, the subsequent manual withdrawal of theneedle is often regarded by some patients as painful.

Automatic cannula insertion devices have been developed to address theseissues. Typically, a cannula is included in a stand-alone device calledan insertion or injection set. In addition to the cannula and needle,the insertion set often includes a housing to which the cannula isattached during use. The housing may have an adhesive pad for adheringthe housing to the skin of the patient during use, as well as aninternal void or chamber that is penetrated by an inlet and a septum.The needle passes through the septum, void, and into the lumen of thecannula. After insertion, the needle is withdrawn from the septum, whichseals the void. Thereafter, a tube is connected to the inlet, therebyplacing the lumen (via the void) in fluidic communication with aninfusion device, intravenous (IV) drip bag, or other medical equipment.The above-described insertion sets may be acceptable for some patients,but the attached tube and medical device can be obtrusive, which may beundesirable in some cases. It would be desirable then, to incorporatethe functionality of an insertion set into an infusion device tominimize the attendant tubing and complications involved in connectingthe insertion set to the infusion device.

SUMMARY OF THE INVENTION

The invention relates to an insertion device for a cannula, wherein thecannula is carried on a needle, as well as a cannula configuration thatallows for automatic alignment of an inlet on the cannula with a channelin an infusion device, without having to separately connect a tubethereto. In combination with a drive apparatus, the needle can bedisplaced from a retracted position into an extended position, thusforming a fluidic connection.

During an insertion procedure described herein, a cannula is used inconjunction with a needle. The needle is used to penetrate the body.Subsequently, the needle is withdrawn from the body, allowing thecannula to remain in its inserted position. Consequently, one advantageof the invention is to increase the comfort of a patient during theinsertion and withdrawal of a catheter or cannula. This benefit may beachieved with a device for the insertion of a cannula of the typedescribed herein, wherein the needle, after reaching its extended state,can be withdrawn quickly and automatically by a retraction apparatus.

One embodiment of the invention allows the needle to not only quicklypenetrate the body tissue (i.e., blood vessel, organ, or other bodypart) of a patient, but due to aid from the retraction apparatus, theneedle is quickly withdrawn from the body tissue and simultaneously, theinserted cannula remains within the body tissue. In this way, since theneedle is relatively quickly withdrawn from the body tissue, a much morecomfortable sensation is experienced than that associated with a slowerinsertion and withdrawal. Further, any sensation is transient. Theretraction apparatus is activated, in any case, when the needle isalready within the patient's tissue, that is to say, when the needle isin its extended position. Thereby, it is possible for the operator toinsert the needle and its associated cannula to a sufficient depth toreach a desired position within the body tissue.

In one embodiment, the driving element or needle plunger is subject tothe force of a spring. The spring can be prestressed and restrained byan arresting apparatus from which it is released to carry out itsdriving function. The spring acts upon a drive mechanism, which includesat least one first part (e.g., a plunger), which is in driving contactwith a free end of the spring and the drive mechanism includes oneseparate second part (e.g., a support structure), indirectly activatedby the spring. Thus, the second part is made slidingly displaceable in afirst direction by means of the motion of the first part and,conversely, separates itself therefrom upon a movement of the first partin an opposite direction. Such an arrangement reduces the weight, whichcontributes to momentum during the retraction of the needle.Simultaneously, the needle, upon its movement from the retractedposition into the extended position, stabilizes the cannula sufficientlywhen so projected, so that that the insertion procedure can be reliablycarried out.

In certain embodiments, the needle, which is seated in the second part,is releasably held. Accordingly, the needle can disengage itself fromthe second part at the outset of a retracting motion and can bewithdrawn without obstruction. In this way, the needle is notpermanently affixed to the drive mechanism, an advantage which can beusefully employed to even move the needle more quickly, i.e., throughmore rapid increments of retractive motion.

At the time that the needle is disconnected from the second part,nothing more than the weight of the needle need be placed in motion, anadvantage which allows undiminished acceleration. Since the movement ofa needle within the body tissue can be uncomfortable, it is helpful ifthe displacement of the needle can be accelerated so that it can beremoved from the tissue in a minimal amount of time.

In one embodiment, the activation of the needle is subjected to force bya separate retraction spring (compression type) dedicated thereto, whichacts in a direction from the second part toward the first part. It ispossible, then, that this retraction spring serving the needle can beemployed to force the now-released needle away from the second part in adirection that withdraws it from the penetrated body tissue. The secondpart can include at least one holding element that retains the needletherein, and permits the needle to be subsequently retracted from anextended position. The concept of “retraction” or “withdrawal,” as usedherein, is used to describe removal of the needle from the lumen of thecannula after full insertion or extension of the cannula. The method ofconstruction of the holding element, that is, as to whether itsretaining characteristic is due to mechanical, magnetic, or otherinduced forces, is of secondary importance for the purpose of thisdescription. During the interim within which the needle has not yetreached its extended position, the holding element acts to affix theneedle within the second part. As soon as the second part has reachedits final and extended position, the retention of the needle is nolonger necessary. Accordingly, at this time, the holding elementreleases the needle, so that it departs from the second part andextricates itself therefrom.

In one embodiment, the holding element is located in the exposed surfaceof an end of the second part, from which the needle projects. From thisend surface of the second part, when in extended position, the tip ofthe needle comes into contact with another surface. This so designated“other surface” can well be a surface of the patient's tissue, whereinthe cannula is in the process of being inserted. Otherwise, thecontacted surface can even be a lining of a device housing. In any case,by means of an impact of the second part against a target surface, theholding element is released, i.e., the retention of the needle thereinis ended.

In one embodiment, the first part possesses an activation element,which, at the completion of needle extension, acts upon the needleholding element. In this case, the first part is employed to relieve theholding element of the second part from its retaining function. By meansof the mechanical structure of the holding element the needle isreleased when the position of the holding element changes. If theprinciple of construction of the holding element is electromagnetic incharacter, then the activation means may open a switch, which willinterrupt a supply of current to the magnetic system. In such a case,the magnet becomes deprived of its power. Additionally, it iscontemplated to displace a working magnet thereby terminating itsholding ability. Additional methods for this removal of holding powerare contemplated.

In an embodiment of the invention, the activation means of the firstpart and also the holding element possess complementary, coacting,inclined surfaces. Motion of the activation means toward the holdingelement, which is carried out in a direction parallel to the needle, canbe diverted to a motion not parallel, but rather angular therefrom. Inthis alteration, the angular direction could even be at a right angle.

The needle is supported by the said retraction spring to lie against thefirst part. This constructive support can be used with or without aholding element. The retraction spring assures that the needle can besecured by means of one or more projections on the second part. Thissecurement would hold the needle in place during the movement of thedrive mechanism. When the needle and catheter begin to penetrate intothe body tissue, the needle itself is subjected to a reaction force,which, without an element for holding, finally causes the needle to actcontrary to the force of the retraction spring. Nevertheless, by meansof an appropriate dimensioning of the retraction spring, arrangement canbe made such that the needle-catheter combination penetratessufficiently far into the subject body tissue.

The first part may possess a second holding means to which the needlebecomes secured during a withdrawal from the extended position. Thisholding means retains the needle firmly within the first part, so thatthe needle retracts by means of the reversing motion of the first partof the drive mechanism.

In this arrangement, a second holding means consists of a cavity in thefirst part. The needle, or if necessary, a thickened section of theneedle, is then simply retainingly inserted into the first part andsubsequently held there by a force of friction. The necessary frictionalforces can be increased by an appropriate surfacing of the interior ofthe cavity and/or increasing the size of the active exterior of theneedle.

The first part and the second part are located in a housing. Thishousing possesses in the area remote from the drive spring, an end facethat blocks the travel of the second part. If the second part makescontact with the end face of the housing, or places itself very closethereto, it will be held in position by the above described holdingmeans. This prevents the second part from following the first part as itwithdraws.

A storage means for medicaments or a communicating fluidic connectionfor the cannula is located in the second part. In one embodiment, thesecond part is secured to the cannula, so that after the withdrawal ofthe needle, the cannula remains in its extended position in the tissueof the patient. The medicament can then be infused through the cannulainto the body. An input or outtake branching can also be joined to thecannula line. By means of the input or outtake device, a medicament canbe applied or blood or the like can be withdrawn from the body.

The drive mechanism functions with the aid of an inclined surface onwhich is formed a path for movement of the needle, since the inclinedsurface moves in a direction transverse (or angular) to that of theneedle. This path, which accommodates the perpendicular travel of theneedle, ends in a steplike termination. With such a termination asdescribed, the functional movement of the needle is thus decoupled fromits penetrative direction. The needle is forced by the inclined surfaceand accordingly slides along this inclined surface, being augmented bythe intervention of the drive mechanism. Because of the inclinedsurface, the needle is subjected to an angular resultant force, whichcauses the needle to move. Upon an activation of the drive mechanism, anadditional force may be applied to alter the direction of motion of theneedle.

The above “step” is formed by a recess in the inclined surface. Theneedle, or an integral element thereof, drops into the recess once ithas reached its final, extended position. This recess also blocks anyadditional movement of the inclined surface. The inclined surfacepossesses a helical configuration and moves in a rotatable body. Thisrotatable body comprises, for example, a cylindrical shape, and can forma part of the drive mechanism. When this body is rotated, then aneffective area of the inclined surface forms a slidingly spiral path forthe needle alone or for both the needle and the drive mechanismtogether. As the needle moves from its withdrawn position into itsextended position it may move with the drive mechanism. In this way, arelatively long length of the sliding path on the helical inclinedsurface is achieved with minimum space and an excessive dimensioning ofthe insertion mechanism is thereby avoided.

In one aspect, the invention relates to a cannula insertion deviceincluding a housing defining an opening for receiving therethrough acannula and further defining a channel, and a cannula forming a lumen,the cannula adapted for sliding movement within the housing from aretracted position to an extended position, wherein when the cannula isin the retracted position, the lumen is located remotely from thechannel and the channel is in fluidic communication with the opening,and when the cannula is in the extended position, the lumen is influidic communication with the channel. In an embodiment of the aboveaspect, the cannula insertion device further includes a base connectedto the cannula, the base defining an internal chamber in fluidiccommunication with the lumen. In another embodiment, the base furtherdefines a chamber extension in fluidic communication with the internalchamber. In yet another embodiment, when the cannula is in the extendedposition, the chamber extension is aligned with the channel. In stillanother embodiment, a wall of the base defines the chamber extension.

In another embodiment of the above aspect, the base includes a resilientsheath, the sheath defining a port substantially aligned with thechamber extension. In another embodiment, when the cannula is in theextended position, the port is aligned with the channel. In yet anotherembodiment, when the cannula is in the extended position, the sheathseals the opening. In still another embodiment, the cannula insertiondevice further includes a plunger for driving the cannula from theretracted position to the extended position. In another embodiment, thecannula insertion device further includes a needle disposed in the lumenwhen the cannula is in the retracted position. In another embodiment,the needle is adapted to be automatically withdrawn from the lumen whenthe cannula is in the extended position. In another embodiment, theneedle is adapted to be automatically disconnected from the plunger whenthe cannula is in the extended position.

In another aspect, the invention relates to a method of inserting acannula, the method including the steps of providing a housing definingan opening for receiving therethrough a cannula and further defining achannel, providing a cannula forming a lumen, the cannula adapted forsliding movement within the housing from a retracted position to anextended position, and extending the cannula from the retractedposition, in which the lumen is located remotely from the channel andthe channel is in fluidic communication with the opening, to theextended position, in which the lumen is in fluidic communication withthe channel. In an embodiment of the above aspect, the method furtherincludes the step of piercing a skin of a patient with a needle and thecannula as the cannula moves from the retracted position to the extendedposition. In another embodiment, the method further includes the step ofwithdrawing the needle from the lumen automatically when the cannula isin the extended position. In yet another embodiment, a plunger extendsthe cannula from the retracted position to the extended position, theplunger in contact with the needle. In still another embodiment, themethod includes the step of disconnecting the needle from the plungerwhen the cannula is in the extended position. In another embodiment, themethod includes the step of sealing the opening with the cannula whenthe cannula is in the extended position.

BRIEF DESCRIPTION OF THE FIGURES

Other features and advantages of the present invention, as well as theinvention itself, can be more fully understood from the followingdescription of the various embodiments, when read together with theaccompanying drawings, in which:

FIG. 1 is a schematic sectional side view of an insertion device in aretracted position in accordance with one embodiment of the invention;

FIG. 2 is a schematic sectional side view of the insertion device ofFIG. 1 in an intermediate position;

FIG. 3 is a schematic sectional side view of the insertion device ofFIG. 1 in a second intermediate position;

FIG. 4 is a schematic perspective view of a portion of an insertiondevice in accordance with another embodiment of the invention;

FIG. 5 is a schematic sectional side view of an insertion device inaccordance with another embodiment of the invention;

FIG. 6 is a schematic side view of an insertion device in a retractedposition in accordance with another embodiment of the invention;

FIG. 7 is a schematic side view of the insertion device of FIG. 6 in awithdrawn position;

FIG. 8 is a schematic perspective view of an insertion ramp inaccordance with one embodiment of the invention;

FIG. 9 is a schematic side view of an insertion device in a retractedposition in accordance with another embodiment of the invention;

FIG. 10 is a schematic side view of the insertion device of FIG. 9 in anextended position;

FIG. 11 is a schematic side view of the insertion device of FIG. 9 in awithdrawn position;

FIG. 12 is a schematic top sectional view of the insertion device ofFIG. 9;

FIG. 13 is a schematic top sectional view of the insertion device ofFIG. 11;

FIG. 14 is a schematic diagram of an exemplary infusion devicemicrocircuit;

FIG. 15A is a schematic perspective view of an automatically-aligningcannula in accordance with one embodiment of the present invention;

FIG. 15B is a schematic top view of the cannula of FIG. 15A;

FIG. 16 is a schematic side sectional view of the cannula of FIG. 15A ina retracted position from an associated housing;

FIG. 17 is a schematic side sectional view of the cannula of FIG. 15A inan extended position;

FIG. 18 is a schematic side sectional view of the cannula of FIG. 15A inthe retracted position;

FIG. 19 is another schematic side sectional view of the cannula of FIG.15A in the extended position; and

FIGS. 20A-20C are schematic side sectional views depicting a method ofinserting an automatically-aligning cannula in accordance with oneembodiment of the invention.

DETAILED DESCRIPTION

FIG. 1 depicts an embodiment of an insertion device for a catheter 1having a housing 2, within which a needle 3 is affixed by a needleholder 4. On the end remote from the needle holder 4, the needle 3carries a catheter or cannula 5. In this document, the terms “catheter”and “cannula” are used interchangeably and without limitation todescribed any tube-like implement to deliver fluids to any body part ofa patient. In the attached figures, for the sake of clarity, therepresentation of the catheter 5 is enlarged. In general, the diameterof the catheter 5 is only slightly larger than the outside diameter ofthe needle 3.

The needle 3, in a manner not shown, is so enveloped by a guide in thehousing 2, that it can only move in a direction parallel to itslongitudinal axis L. The design allows the needle 3 to be displaced intoan extended position. In this extended position of the needle 3,depicted in FIG. 2, the catheter 5 is positioned at least partiallyoutside the housing 2 and thus penetrating into body tissue 6.Designated here as “body tissue” is to be understood, for example, theskin, vein, or organ of a patient.

In order to move the needle 3 in conjunction with the catheter 5, adrive mechanism V is provided. Alternative drive mechanisms are alsodescribed in FIGS. 6-13. The drive mechanism V depicted in FIGS. 1-3possesses a drive spring 16 which powers the drive mechanism V.Described in greater detail, the drive spring 16 acts upon a first partor plunger 17, which is positioned against a second part or supportstructure 18. This support structure 18 can be loosely affixed to thefirst part or plunger 17 or, alternately, secured thereto by anadditional spring (not shown), which would abut the housing 2. Inanother embodiment, a holding means can be installed to combine thefirst and second parts, respectively 17 and 18. This holding means maybe any type of chemical, mechanical, electromagnetic, or other fastener.In any case, the two parts 17 and 18 are made to move under the force ofthe drive spring 16 in the direction of the tissue 6 of a patient, asdepicted by arrow 27 a.

In the support structure 18, the needle 3 is retained, in particular bymeans of two needle holding elements 19. These holding elements 19project outward from the patient proximal end face 20 of the supportstructure 18. The two holding elements 19 each include endwise, remotefrom the end face 20, a hook 21, which is shown in FIGS. 1 and 2 aslocated on the top of the needle holder 4. The needle holder 4 supportsitself against the support structure 18 by means of a retraction spring22. However, this needle holder 4 can only be displaced in the directionof the plunger 17 to such extent that it is permitted by the needleholding elements 19.

Each of the hooks 21 on the needle holders 19 possesses on the endproximate to the plunger 17 an inclined outer surface 23. The plunger 17is equipped on the side proximate to the support structure 18 withprojections having inclined surfaces 24, which are complementary to theabove-mentioned surfaces 23. When the parts 17 and 18 are sufficientlydisplaced by the force of the drive spring 16, the needle holdingelements 19, projecting out of the end face 20 of the support structure18, make contact with a base wall 25 of the housing 2. The holdingelements 19 are detachably connected to the support structure 18.Accordingly, as the holding elements 19 make contact with the base wall25, spring 16 continues to drive support structure 18 toward the basewall 25, causing the holding elements 19 to detach from the supportstructure 18. The continued movement of the support structure 18 in thedirection of the base wall 25 forces the needle holding elements 19 inthe direction of the plunger 17, until the complementary inclinedsurfaces 23, 24 contact one another. At this point, the holding elements19 are displaced outward and thus free the needle holder 4 from thesupport structure 18. With this arrangement, the needle 3, activated bythe force of a retraction spring 22, is moved in the direction of theplunger 17. At this point of operation, the compressed retraction spring22 initially displaces the needle 3 with a relatively greateracceleration. Accordingly, the needle 3 is forced backward out of thebody tissue 6.

The first part includes a recess 26, into which the needle holder 4 canretreat under the force of the retraction spring 22. This recess 26 is,in this case, simply shown as a cavity sized to match the needle holder4. Other types of recesses are also contemplated. In function, therecess 26 accepts the needle holder 4 with the thereto affixed needle 3and, at the same time, firmly secures the needle 3, so that, after theinitial movement, the needle 3 can be retracted along with plunger 17out of its extended position. The needle holder 4 may be secured withinthe recess 26 by mechanical, chemical, magnetic, friction, or othermeans. At the same time, the needle 3 is relieved of the catheter 5,which remains in its embedded position in the patient's tissue 6. Thisdisplacement of parts is shown by the arrow 27 b.

The support structure 18, in this state of the operation, remains in theposition shown in FIG. 3. The support structure 18 may be equipped withlateral lugs 28, which may fit into clamps 29, when the supportstructure 18 is fully extend and the catheter inserted into the patienttissue 6. These lugs 28 and clamps 29 are depicted in FIG. 4. The clamps29 firmly secure to the lugs 28, so that the support structure 18 liesfixedly on the base wall 25 of the housing 2. In an alternative to thedepicted lugs and clamps, matching male and female ports may be locatedon the support structure 18 and base wall 25 to hold the supportstructure 18 in place against the base wall 25. Additionally, lugs beused in embodiments of the catheter insertion device that do not utilizea support structure. For example, the automatically aligning cannuladepicted in FIG. 14 utilizes lugs for alignment, secured directly to thecatheter base. This embodiment is described in more detail below.

Additionally, means can be provided that exert a clamping force betweenthe support structure 18 and the needle 3 or between the catheter 5 andthe needle 3. In such a case, during a displacement of the supportstructure 18, forces would be transferred to the needle 3, which wouldbe sufficient to firmly align the needle 3 in place during itspenetration into the body tissue 6. When the catheter 5 and the needle 3attain their desired penetration, i.e., reach the extended position,then the clamping of the holding means is relaxed and the retainingfriction attributable thereto against the needle 3 is removed, so thatthe needle 3 is free to be withdrawn in the manner described above.

The support structure 18 may possess a stand-alone storage means formedicaments, whereby the medicaments can be delivered through thecatheter 5. Alternatively, the cannula insertion device described hereinmay be integrated with a medication delivery device having its ownstorage means of medicament. In such an embodiment, the supportstructure 18 can be provided with an opening 31, by means of which aninput of medicament supply or the like can be effected. Such an openingwould also permit the input or removal of materials, for instance ofblood or sera. Such an embodiment is described in more detail withregard to FIGS. 14-20C.

FIG. 5 shows an alternative embodiment of the needle retraction systemdepicted in FIGS. 1-3. In this embodiment, needle holder 4 is providedwith a lateral projection 36, which is acted upon by the retractionspring 22. A release apparatus 37 prevents the retraction spring 22 fromretracting the needle 3 prior the needle 3 reaching the extendedposition depicted in FIG. 5. Once the needle 3 is in the extendedposition, however, the release apparatus 37 frees the retraction spring22 and the needle 3 is withdrawn from the body tissue 6 in the directionof arrow 38. In the withdrawn position, the needle holder 4 would besecured within the recess 26. As the plunger 17 retracts, the needle 3,retained in the recess 26, is thereby fully withdrawn from the tissue 6.

The insertion device 101 for a cannula, shown in FIGS. 6-8, includes ahousing 102, in which the needle 103 coacts with needle holder 104 andcannula 105. Conveniently, a combination of the needle 103 and theneedle holder 104, for example, could be constructed as a lancet. Inthis embodiment, the needle holder 104 is shown as a one-piece object.This could otherwise be made as a combination with the two parts 17 and18, in the manner presented and explained in FIGS. 1-3. The needleholder 104 includes a contacting surface 107 on the end remote from theneedle 103.

A cylindrical insertion ramp body 108 is located within the housing 102.The ramp body 108 is provided with a pin 109, about which it can rotatewithin the housing 102. Additionally, a cover 110 for the housing 102has a positioning pin 111 which is designed to penetrate into a recess112 in the ramp body 108, so that the ramp body 108 can align itself onboth axial ends (pin 111 and pin 109 form an axis R around which theramp body rotates) to prevent dislocation or skewing of the body 108.The housing cover 110 is preferably adhesively affixed to the housing102 or it may be welded thereto; other methods of connection arecontemplated.

The ramp body 108 includes an inclined, helically disposed surface 114which is provided with a path for movement of an object thereon. For thesake of clarity, a separation is depicted between the needle holder 104and the ramp body 108. In reality, the needle holder 104 lies directlyon, and in complementary contact with, the helical surface 114 of theramp body 108.

As the ramp body 108 rotates about its axis R, the needle holder 104slides along the surface 114, forcing the needle 103 and cannula 105downward (as depicted in FIGS. 6-7) such that the penetrative needle tip115 exits the housing 102. As the tip 115 penetrates the tissue 106, thecatheter 105 is inserted into the tissue 106.

The degree of force in the drive mechanism for the rotation of the rampbody 108 is furnished by a drive spring 116, which is designed toproduce a torsion force about the axis R. Consequently, this drivespring 116 is provided with an end (not shown) abutting the housing 102and having the other end affixed to the ramp body 108. A releasablearresting element (not shown) retains the ramp body 108 against theforce of the prestressed drive spring 116. After the release of thearresting holding element, the ramp body 108 rotates in reference to theneedle holder 104 by the force of the drive spring 116. This rotationdisplaces the needle holder 104 and therewith the needle 103 in thedirection of body tissue 106.

The needle holder 104 is supported by means of a retraction spring 117,which abuts against the housing 102 at a section 118 thereof. Thishousing section 118 is proximate the cannula 105, when the needle 103 isplaced in the retracted position as shown in FIG. 6. The retractionspring 117 also assures that the needle holder 104 is in contact withthe inclined, helical surface 114 and that such contact is maintained.Upon rotation of the cylindrical body 108, the retraction spring 117 isadditionally stressed. This spring is designed in an open spiral manner,which may surround the needle 103 lying between the section 118 of thehousing and the needle holder 104. This retraction spring 117 can alsoact upon another location on the needle holder 104, especially on thefirst part 17 as seen in the FIGS. 1-3.

During the rotation of the ramp body 108, the contacting surface 107 ofthe needle holder 104 lies on a predetermined, circularly running pathon the inclined surface 114. At the end of this circular running path,the ramp body 108 drops off as a recess 119, which is so dimensionedthat the needle holder 104 can fit therein, as depicted in FIG. 7.Accordingly, it is only possible for the ramp body 108 to rotate untilthe needle holder 104 secures itself within the recess 119.

The needle 103, with the cannula 105, is now inserted into the bodytissue 106 by the force of the driving spring 116. The lift of theneedle holder 104, which is created by the inclined surface 114, issufficient to serve for this purpose. As soon as the ramp body 108 hassufficiently rotated so as to align the recess 119 with the needleholder 114, no further movement of the needle 103 into an extendedposition may occur. Instead, a retraction motion now occurs, powered bythe force of the retraction spring 117. Since the needle holder 104drops off the inclined surface 114 into the recess 119, the retractionmovement is instantaneous. Simultaneously, the ramp body 108 ceases itsrotation, due to the fact that the needle holder 104 is now seated inthe said recess 119, as depicted in FIG. 7.

As soon as the needle 103 has set the cannula 105 within the body tissue106 and has been withdrawn, the housing 102 can be lifted away from thebody tissue 106. In the presently described embodiment, an infusionapparatus 120 containing the housing 102 is depicted. When the housing102, as mentioned above, is lifted away from the infusion apparatus base120 a, then the cannula 105 is freely accessible. The cannula 105 maythen be connected to an infusion channel (not shown). FIG. 8 shows theramp body 108 with the recess 119 in the inclined surface 114 as well asthe positioning pin 109.

Another embodiment of a device for insertion and retraction of theneedle is shown in the FIGS. 9-13. The insertion device 201 includes ahousing 202, in which a needle 203 is located along with a needle holder204 and a catheter 205. The needle holder 204 is secured in its positionin the housing 202 by a holding means 206. The holding means 206 has aprojection 207 which, when inserted into a recess 208 on the needleholder 204, prevents activation of the device 201. The holding means 206is movable in the direction shown by arrow 209, which allows the needleholder 204 to be released. The needle holder 204 can, in turn,incorporate both parts 17 and 18, as depicted in FIGS. 1-3. The holdingapparatus 206 can then successfully act upon the plunger 18.

A drive mechanism 210 has a lever 211, which can pivot about a pin 212.The lever 211 has further a rod 213, which enters into a cavity 214 inthe needle holder 204. As depicted, the lever 211 is subjected toclockwise rotation (compare FIGS. 9 and 10) by the force of a drivingspring 215. This driving spring 215 has one termination as a first leg216 that abuts the housing 202 and also includes a second leg 217 thatacts upon the lever 211. A retraction spring 218 is placed about anaxial pin 219. This retraction spring 218 has a first leg 220 that abutsa housing secured projection 221 and also includes a second leg 222 thatacts upon a pin 223 that projects from the needle holder 204. Theretraction spring 218 exerts a lesser force upon the needle holder 204than does the driving spring 215.

The position of the driving spring 215 is controlled by a guide member224, which is formed by the surface of a housing projection 225. Theprojection 225 has a limited longitudinal dimension which runs parallelto the needle 203. To insert the cannula 205 into body tissue 226, theinfusion device 120 first is placed against the body tissue 226. Theholding means 206 is moved in the direction of the arrow 209, so thatthe projection 207 is brought out of contact with the recess 208 in theneedle holder 204.

Thereafter, the needle holder 204 is displaced in a direction toward thebody tissue 226 by means of the force of the driving spring 215. Guides227 may direct the movement of the needle 203 in a straight line towardthe body tissue 226. As the driving spring 215 forces the needle holder204 into the extended position, the driving spring 215 slides along theprojection 225. In accord with the FIGS. 9-11, the driving spring 215,lies between the projection 225 and the needle holder 204, as seenperpendicular to the plane of the drawing, thus being behind the needleholder 204, as depicted in FIGS. 12 and 13.

FIG. 10 depicts the needle 203, with its attached cannula 205, in anextended position, so that the cannula 205 is shown as inserted into thebody tissue 226. The force necessary for this action is derived from thedriving spring 215 which has been prestressed. During its movement fromthe retracted position (FIG. 9) to the extended position (FIG. 10) themovement of the driving spring 215 is regulated by the guide 224. Whenthe needle reaches the extended position, the driving spring 215 dropsaway from the guide 224 and the projection 225, so that it then exertsno force against the needle holder 204. This is shown in FIGS. 12 and13.

FIG. 12 depicts a top view of the insertion device 201 in the retractedposition. The rod 213 is located within the recess 214 of the needleholder 204, and therefore, in contact with the needle holder 204.Accordingly, the driving spring 215 is held actively against the guide224 of the projection 225.

FIG. 13 depicts the insertion device 201 in the withdrawn position.Here, the rod 213 has lost engagement with the recess 214, due to thetermination of the projection 225, and corresponding loss of engagementbetween the guide 224 and the driving spring 215. The operativeconnective relationship between the needle holder 204 and the drive unit210 (FIG. 11) has been interrupted. This occurs at the time the needle203 is in the extended position. Once the operational relationshipbetween the driving unit 210 and the needle holder 204 has beeninterrupted, the retraction spring 218 is able to act upon the needleholder 204. As shown in FIG. 11, this causes the needle 203 to bereturned to the withdrawn position. The retraction spring 218 has theability to receive a small, prestressing force. However, itsprestressing is generally due to the movement of the needle holder 204.The force of the retraction spring 218 may be effectively smaller thanthat of the driving spring 215.

In another embodiment, it is possible to permit a spring (not shown) toact transversely to the direction of driving movement of the insertiondevice 201, delivering force to lever 211 and/or to the driving spring215. In this case, when the projection 225 terminates, the lever 211and/or the driving spring 215 can be moved transverse to the directionof movement of the needle 203. It is further possible that an additionalguide may be provided, which would be placed on that end of the lever211, which is opposite the projection 225 and which would move the lever211 and/or the driving spring 215 out of the position of FIG. 12 andinto the position shown in FIG. 13.

FIG. 14 is a schematic diagram of an exemplary infusion devicemicrocircuit 250. The various cannula insertion devices described abovemay be utilized with the depicted microcircuit, or similarmicrocircuits, to establish a fluidic connection between themicrocircuit 250 and a patient. Other infusion devices havingmicrocircuits are described in U.S. Published Patent Application No.2005/0165384, published Jul. 28, 2005, the disclose of which is herebyincorporated by reference herein in its entirety. The microcircuit 250includes a reservoir 252 that is, in this case, comprised of anelastomer bladder. A fill port 254 is used to introduce insulin to themicrocircuit 250. In this microcircuit 250, introducing insulin via thefill port 254 fills both the reservoir 252 and a variable-volume bolusreservoir 256. Check valves 258 prevent backflow of insulin in a numberof locations.

During use, insulin is forced from the reservoir 252 by the elastomerbladder, through a filter 260, and into two parallel flowpaths, a basalflowpath 262, and a bolus flowpath 264. The basal flowpath 262 deliversa constant dose of insulin to a user; the bolus flowpath 264 delivers abolus dose of insulin to the user as needed or desired by the user. Thebasal flowpath 262 includes a pressure sensor 266 or other flow sensorin communication with the flowpath 262. To deliver a bolus via the bolusflowpath 264, the user presses a button 268 that drives a single stroke(delivering a single dose) of a bolus displacement chamber 270 and openstwo valves 272. The valves 272 are in series for safety purposes. Flowrestrictors 274 dictate the fluid flow through the flowpaths 262, 264.The parallel flowpaths 262, 264 join at a common channel 276 just beforean internal chamber or a cannula void 278. The cannula void 278 isformed in a cannula base 280, which allows a point of connection to acannula 282. The cannula 282 extends below the skin 284 of a user, thusdelivering the insulin subcutaneously. In the following figures,embodiments of cannulas are described that may be used in conjunctionwith the insertion devices described herein to automatically formfluidic connections within devices having microfluidic circuits.

FIG. 15A is a schematic perspective view of an automatically-aligningcannula 300, that includes two major components: a cannula base 302 anda cannula 304 secured thereto. The cannula base 302 includes one or morelugs 306 that project outward from the base 302. In the depictedembodiment, two lugs 306 are located flush with a top surface 308 of thebase 302, although other locations are contemplated depending on theconfigurations of a housing well (described below). A resilient sheath310 surrounds the base 302 and serves at least two purposes. First, ithelps form a friction fit between the aligning cannula 300 and a housingwell, when the cannula is in the extended position. Second, it helpsform a seal at the interface between a chamber extension 312 (thatcommunicates with a chamber within the base 302) and a channel locatedwithin a device housing (described below). A port 314 in the sheath 310aligns with the chamber extension 312. The top surface 308 of the base302 defines a void 316 for passage therethrough of the insertion needle.A self-sealing septum seals the void 316 to prevent leakage of fluidfrom the internal chamber once the insertion needle is removed.

Other configurations of sheaths are also contemplated. Alternativesheaths may entirely encase the catheter base, or may cover a discretearea of the base, generally surrounding the chamber extension thatpenetrates the wall of the base. In an alternative embodiment of thecatheter base, the base itself may be entirely constructed of resilientmaterial. In such a case, a more rigid top (e.g., in the form of alaminate construction) and lugs may be desirable to ensure that theinsertion mechanism can properly exert a driving force against the base.

FIG. 15B is a schematic top view of the automatically-aligning cannulaassembly of FIG. 15A. In the extended position, the cannula base 302 ofthe automatically-aligning cannula 300 is secured within a housing well330, due to compression of the resilient sheath 310 surrounding the base302. In this figure, the internal chamber 334 is depicted below theseptum 336 that seals the void 316. The housing well 330 may be eitherintegral with or otherwise secured to a housing 332 itself. The depictedembodiment shows an insertion device integral with a medical deliverydevice (e.g., an infusion device). Other embodiments and applicationsare contemplated. The housing well 330 defines one or more verticalslots 338, sized and configured to receive the one or more lugs 306extending from the cannula base 302. The slots 338 are located to ensurealignment of the chamber extension 312 with the channel 340 when thecannula 300 is in the extended position. The channel 340 may be formedwithin a housing wall or riser 342 or may be a discrete tube secured tothe housing 332.

FIG. 16 is a schematic side section view of the automatically-aligningcannula 300 in a retracted position 360 above the housing well 330. FIG.18 shows the same configuration, in a section oriented orthogonal to thesection depicted in FIG. 16. In FIG. 16, internal chamber 334 is influidic communication with the exterior of the base 302 (via the chamberextension 312 and port 314). In turn, a lumen 362 formed within thecannula 304 forms a fluidic path from the chamber 334, out of the deviceand into a patient, when the cannula 304 is in the extended position(FIGS. 17 and 19). The housing well 330 is formed by an annular wall 364that, as described above, forms therein a number of slots 338 for matingwith the lugs 306. In the depicted embodiment, the housing well 330 isnot formed integrally with the housing 332, but as described above, maybe so formed in other embodiments. The annular wall 364 defines atapered frustoconical opening 366 sized to receive the cannula base 302.This opening 366 is in direct fluidic communication with the environment368 outside of the device housing 332. When the housing 332 is attachedto the skin of a patient, the opening 366 will abut the skin. Asdepicted in FIG. 16, when in the retracted position 360, the channel 340is in direct fluidic communication with the opening 366 and,consequently, the outside environment 368.

FIG. 17 is a schematic side section view of the automatically-aligningcannula 300 in an extended position 400 within the opening 336 of thehousing well 330. FIG. 19 shows the same configuration, in a sectionoriented orthogonal to the section depicted in FIG. 17. Notably, in theextended position 400, the resilient sheath 310 firmly secures thecannula base 302 within the tapered opening 336 formed within thehousing well 330, thus sealing the opening 336. Additionally, thetapered shape of the base 302 and the location of the resilient sheath310 help ensure alignment of the chamber extension 312 and the channel340. The embodiment depicted in FIG. 17 depicts the chamber extension312 and the channel 340 as being approximately the same diameter. Thisis not required; in fact, it may be advantageous to size the chamberextension 312 larger than the channel 340 to help ensure that those twoconduits will be in fluidic communication when the cannula base 302 isin the extended position 400.

In the extended position 400, the cannula 304 extends into a patient402. While this application refers generally to insertion of the cannula304 into the skin of a patient for the delivery of insulin, other usesare also contemplated. For example, the insertion device could be usedto insert a cannula or catheter into a blood vessel or directly into abody organ. The automatically-aligning feature of the insertion devicedescribed herein immediately forms a fluidic connection, by aligningopenings in mating surfaces, and serves the same advantages in anynumber of applications.

FIGS. 20A-20C depict steps associated with one embodiment of inserting aautomatically-aligning cannula 502. The figures depict the insertiondevice 500 in the retracted (FIG. 20A), extended (FIG. 20B), and needlewithdrawn (FIG. 20C) positions. In the retracted position (FIG. 20A),automatically-aligning cannula 502 is aligned along an insertion deviceaxis L with housing well 504. Automatically-aligning cannula 502includes a base 506, a cannula 508, and a needle 510. The needle 510penetrates a self-sealing septum 512 and passes through first aninternal chamber 514 in the base, then through a lumen 516 formed by thecannula 502. The needle end 510 a may terminate at or below the bottomof the cannula 508. As mentioned above, the outer diameter of the needle510 and the inner diameter of the cannula 508 (i.e., the size of thelumen 516) are typically a close sliding fit. Additionally, the base 506defines a chamber extension 518 through an outer wall 520 of the base506. The chamber extension 518 defines an chamber extension axis A_(E),depicted here as being orthogonal to the insertion device axis L. Otherorientations of the chamber extension axis A_(E) are contemplated,including those perpendicular to or parallel with the outer wall 520.

The outer wall 520 is, in certain embodiments, tapered at an angle arelative to a centerline of the cannula 502 and the colinear insertiondevice axis L. Angle α is also substantially the same as correspondingangle α′ of walls 522 in the housing well 504. In general, angles α andα′ aid in seating the automatically-aligning cannula 502 within thehousing well 504. Channel 524 is located within the wall 522 and definesa channel axis A_(C) that may be orthogonal to axis L, or orthogonal tothe inner edge 526 of wall 522, or otherwise oriented.

To use the insertion device 500, a medical device 528 (for example, aninsulin infusion device) containing the insertion device 500 is firstplaced against the skin 530 of a patient, such that an opening 532defined at least in part by the housing well 504 is proximate the skin530. In this orientation, chamber extension 518 is in fluidiccommunication with the interior of the device 528, as is the lumen 516and channel 524 (since the opening 532 is located proximate the interiorof the device 528, these elements are also in fluidic communication withthe opening 524). In the retracted position, both the chamber extension518 and the lumen 516 are located remotely from the channel 524, or,more specifically, they are not in fluidic communication with thechannel 524. In the retracted position, the chamber extension 518, lumen516, and channel 524 are in fluidic communication only with the interiorof the device 528. However, neither the chamber extension 518 nor lumen516 are in fluidic communication with the channel 524. Fluidiccommunication is not possible between the channel 524 and lumen 516 (viathe chamber extension 518 and internal chamber 514) until the cannulabase 506 is in the extended position. To reach this position, a forceF_(NB) is applied to either or both of the needle 510 and cannula base506 to drive both into the housing well 504.

The extended position of the insertion device 500 is depicted in FIG.20B. In this position, cannula 508 and needle end 510 both penetrate theskin 530 of the patient. Additionally, when in the extended position,channel axis A_(C) and chamber extension axis A_(E) are aligned along acommon axis A. While FIG. 20B depicts actual alignment of axes A_(C) andA_(E), alignment of axes is not required. In other embodiments, forexample, where one or both of the axis are not orthogonal to the deviceaxis L (see FIGS. 16-17, for example), intersection or close proximityof the axes sufficient to ensure fluidic communication from the channel524 to the skin 530 of the patient is acceptable. In other embodiments,sufficient overlapping of areas of the channels would be sufficient toensure fluidic communication. Although depicted schematically in thefigures with significant clearance to facilitate depiction, needle 510is a close sliding fit within the lumen 516 of the cannula 508.Accordingly, to allow unrestricted fluidic communication from thechannel 524 to the patient, needle 510 is removed from the cannula 508.To do so, a force F_(N) is applied to the needle 510 to withdraw it fromthe cannula 508. The various embodiments of the insertion devicesdescribed hereinabove may be used to perform this function. The frictionfit between the cannula base 502 and the housing well 504 retains thecannula base 502 in place and seals the fluidic communication path.

The withdrawn position of the insertion device 500 is depicted in FIG.20C. In this position, the needle 510 has been withdrawn from thecannula base 502, while the base 502 itself remains in place within thehousing well 504. Upon withdrawal, the self-sealing septum 512 closesbehind the needle 510 to ensure a fluid tight seal. Once the needle 510is withdrawn, there is fluidic communication from the device 528 to thepatient, via the channel 524, chamber extension 518, internal chamber514, and the lumen 516. In an alternative embodiment, the needle iswithdrawn completely from the patient, but need not be withdrawncompletely from the cannula base. Since the needle is closely fit withinthe lumen of the cannula, the flow of insulin may still be prevented bythe position of the needle. In that regard, a hollow needle having anopening defined in the sidewall thereof may allow for the passage ofinsulin into the hollow needle. The insulin then passes through thecannula lumen and into the patient.

The embodiments of the automatically-aligning cannula system depicted inFIGS. 14-20C have distinct advantages over known cannula insertionsystems that utilize a hollow needle or tube to form a fluidicconnection between a fluid flow passage and a lumen of a cannula. Insuch systems, the hollow needle penetrates a septum that seals the fluidflow passage prior to use (in this case, the fluid flow passage isalways isolated from the interior of the device by the septum). Incontrast, the disclosed automatically-aligning cannula system does notrequire a needle and septum to create a fluid seal. In that regard, thedisclosed invention presents a more elegant solution that reducesmanufacturing costs and ensures proper operation. The surface-to-surfacesealing configuration of the present invention reduces manufacturingcosts by eliminating the need for an additional needle, septum, orcomplex injection molded parts to incorporate those elements.Additionally, assembly costs are similarly reduced, as the needle andseptum need not be incorporated into the device.

Instead of using a septum and a penetrating needle to ensure a fluidicconnection, the disclosed cannula system aligns two curved surfaces,namely, the curved inner wall of the housing well and the outer surfaceof the frustoconical cannula base. The resilient sheath helps to sealany imperfections formed during the manufacturing process, thusimproving the friction fit of the cannula base within the housing well.Additionally, the sheath aids in sealing the fluidic connection betweenthe chamber extension and the channel, thus preventing leakage of fluid.By eliminating the needle and septum, both the chamber extension and thechannel are in fluidic communication (i.e., not isolated) from theinterior of the device when the cannula base is in the retractedposition. In the extended position, the chamber extension and channelare placed in fluidic communication by alignment, while the connectionis sealed by the sheath.

The various components utilized in the device described herein may bemetal, glass, and/or any type of polymer suitable for sterilization anduseful for delivering insulin or other medicaments subcutaneously.Polyurethane, polypropylene, PVC, PVDC, EVA, and others, arecontemplated for use. More specifically, medical-grade plastics may beutilized for the cannula itself, as well as other components thatcontact or otherwise penetrate the body of the patient. Needles andsprings made from medical-grade stainless steel are also desirable, toprevent failure associated with use.

While there have been described herein what are to be consideredexemplary and preferred embodiments of the present invention, othermodifications of the invention will become apparent to those skilled inthe art from the teachings herein. The particular methods of manufactureand geometries disclosed herein are exemplary in nature and are not tobe considered limiting. It is therefore desired to be secured in theappended claims all such modifications as fall within the spirit andscope of the invention. Accordingly, what is desired to be secured byLetters Patent is the invention as defined and differentiated in thefollowing claims, and all equivalents.

1. A cannula insertion device comprising: a housing defining an openingfor receiving therethrough a cannula and further defining a channel; acannula forming a lumen, the cannula adapted for sliding movement withinthe housing from a retracted position to an extended position in whichthe cannula extends into a body tissue, wherein: when the cannula is inthe retracted position, the lumen is located remotely from the channeland the channel is in fluidic communication with the opening; and whenthe cannula is in the extended position, the lumen is in fluidiccommunication with the channel to deliver a fluid from the channelthrough the cannula into the body tissue; a plunger for driving thecannula from the refracted position to the extended position; a needledisposed in the lumen when the cannula is in the retracted position; aramp body comprising a ramp surface in sliding contact with the plunger;and a drive spring, wherein the drive spring applies a torsion force tothe ramp body for driving the cannula from the retracted position to theextended position.
 2. The cannula insertion device of claim 1 furthercomprising a base connected to the cannula, the base defining aninternal chamber in fluidic communication with the lumen.
 3. The cannulainsertion device of claim 2, wherein the base further defines a chamberextension in fluidic communication with the internal chamber.
 4. Thecannula insertion device of claim 3, wherein when the cannula is in theextended position, the chamber extension is aligned with the channel. 5.The cannula insertion device of claim 3, wherein a wall of the basedefines the chamber extension.
 6. The cannula insertion device of claim5, wherein the base includes a resilient sheath, the sheath defining aport substantially aligned with the chamber extension.
 7. The cannulainsertion device of claim 6, wherein when the cannula is in the extendedposition, the port is aligned with the channel.
 8. The cannula insertiondevice of claim 6, wherein when the cannula is in the extended position,the sheath seals the opening.
 9. The cannula insertion device of claim1, wherein the needle automatically withdraws from the lumen when thecannula is in the extended position.
 10. The cannula insertion device ofclaim 1, wherein the needle automatically disconnects from the plungerwhen the cannula is in the extended position.
 11. A method of insertinga cannula into a body tissue, the method comprising the steps of:providing a housing defining an opening for receiving therethrough acannula and further defining a channel; providing a ramp body comprisinga ramp m surface; providing a cannula forming a lumen, the cannulaadapted for sliding movement within the housing from a retractedposition to an extended position in which the cannula extends into thebody tissue; providing a needle disposed in the lumen when the cannulais in the retracted position; providing a plunger for driving thecannula, wherein the plunger is in sliding contact with the rampsurface; and rotating the ramp body so as to drive the cannula from theretracted position, in which the lumen is located remotely from thechannel and the channel is in fluidic communication with the opening, tothe extended position, in which the lumen is in fluidic communicationwith the channel to deliver a fluid from the channel through the cannulainto the body tissue.
 12. The method of claim 11, further comprising thestep of piercing a skin of a patient with the needle and the cannula asthe cannula moves from the retracted position to the extended position.13. The method of claim 12, further comprising the step of withdrawingthe needle from the lumen automatically when the cannula is in theextended position.
 14. The method of claim 12, wherein the plungerextends the cannula from the retracted position to the extendedposition, the plunger in contact with the needle.
 15. The method ofclaim 14, further comprising the step of disconnecting the needle fromthe plunger when the cannula is in the extended position.
 16. The methodof claim 11, further comprising the step of sealing the opening with thecannula when the cannula is in the extended position.
 17. The cannulainsertion device of claim 1, further comprising: a recess defined by theramp body; and a refraction spring, wherein the retraction spring forcesthe plunger into the recess when the cannula is in the extendedposition, so as to withdraw the needle from the lumen.